1. Field of the Invention
This invention relates to a display apparatus having a touch sensor which can input information by a touch thereof by a user with a finger or the like.
2. Description of the Related Art
Generally, a contact detection apparatus is an apparatus which detects that a finger of a user, a pen or a like element touches with or is positioned in the proximity of a detection face thereof.
A contact detection apparatus called touch panel is known. The touch panel is formed in an overlapping relationship with a display panel such that various buttons are displayed as an image on a display face of the display panel to allow inputting of information through the touch panel in place of ordinary buttons. If this technique is applied to a mobile apparatus of a small size, then such merits as common use of the display apparatus and the button arrangement, increase in size of the screen, space saving of the operation section and reduction of the number of parts are provided.
In this manner, the term “touch panel” generally means a contact detection apparatus of the panel type in combination with a display apparatus.
However, where the touch panel is provided on a liquid crystal panel, the liquid crystal module has an increased overall thickness. Therefore, for example, JP-T-2003-511799 (hereinafter referred to as Patent Document 1) proposes a liquid crystal display device with a touch panel of the capacitance type having a structure suitable for reduction of the device thickness.
A touch sensor of the capacitance type has a driving electrode and a plurality of detection electrodes forming capacitances with the driving electrode.
As an example, it is possible to provide a conductive film, that is, a detection electrode, for a touch panel between an observation side substrate of a liquid crystal display device and an observing polarizing plate disposed on an outer face of the observation side substrate. In this structure, a capacitance type touch panel wherein an outer face of the polarizing plate is used as a touch face is formed between the touch panel conductive film or detection electrode and the outer face of the polarizing plate, and reduction in thickness is achieved.
However, generally a pattern of a driving electrode or a detection electrode is greater than a pixel pitch, and a difference in transmission factor arising from an overlapping manner of electrodes sometimes causes the electrode pattern to be visually perceived through the display face.
Therefore, Patent Document 1 discloses that, for example, in a capacitive type sensor disposed on a display apparatus, a transparent conductor and a substrate are adhered to each other by a bonding agent.
Meanwhile, U.S. Patent Publication No. 2008-0062139 (hereinafter referred to as Patent Document 2) proposes a method of forming a film of ITO on the rear face of a cell of a liquid crystal display apparatus and bonding a polarizing plate to the ITO film.
For the invisualization of an electrode pattern, for example, Japanese Patent Laid-Open No. 2008-129708 (hereinafter referred to as Patent Document 3) discloses a touch panel structure wherein non-conducting transparent electrodes are disposed between patterns upon patterning of detection electrodes so that the transparent electrodes may not be visually recognized by an eye of a person.
If such a countermeasure for the invisualization as disclosed in Patent Document 3 is applied to a touch panel by itself, then the patterns of the transparent electrodes cannot be visually recognized to some degree.